Nice work on your tracker build, looks great!I built the S&T article version back in 2008, the motor went bad. I rebuilt it based on the motor your using. But my Nikon D7000 with the 18-105mm lens kit is heavy. So I added a few pounds of weight to help with balance. I can now get at least 5 minute exposures, with good polar alignment. I also have a green laser pointer, it does not work when the temp drops below freezing. Here's a sample of my tracker at work...